Young brains are unlikely to get cancer from using mobile phones, according to a team of researchers from Switzerland and Scandinavia.

Action Points

Point out that studies of the association between cellphone use and brain tumor in adults have been largely inconclusive, although a work group of the World Health Organization has declared radiofrequency electromagnetic fields to be possibly carcinogenic.

Point out that this study of children and adolescents found that regular users of cell phones were not more likely to have been diagnosed with brain tumors compared with nonusers.

Young brains are unlikely to get cancer from using mobile phones, according to a team of researchers from Switzerland and Scandinavia.

In a case-control study, children and adolescents who were regular users of the devices were no more likely to have been diagnosed with a brain tumor than those who never picked one up, Martin Roosli, PhD, of the Swiss Tropical and Public Health Institute in Basel, Switzerland, and colleagues reported.

"The lack of an exposure-response relationship, given our finding that risk was related to neither the amount of mobile phone use nor the location of the tumor, does not support a causal interpretation," they wrote online in the Journal of the National Cancer Institute.

Yet in a small subset of patients for whom actual data on use were available from the cell phone company, tumor risk was related to the length of time that they owned a phone (OR 2.15, 95% CI 1.07 to 4.29, P<0.001).

It wasn't, however, tied to cumulative hours of use, the researchers reported.

Today, more young children own and use cell phones, which has been a concern because some speculate that they are more vulnerable to potential health effects from the devices.

For adults, studies of the association between cellphone use and brain tumor have been largely inconclusive. The Interphone study, for instance, found no increase in risk of glioma or meningioma with cellphone use -- but there was an increased risk of glioma at an "implausible" level of use, and in some odds ratios, cell phones were even protective against cancer.

To add to the knowledge base, the researchers conducted the CEFALO study -- an international, multicenter case-control study conducted in Denmark, Sweden, Norway, and Switzerland to assess the effects of cellphone use in children and adolescents. The study included all children ages 7 to 19 who were diagnosed with a brain tumor between 2004 and 2008.

The researchers conducted interviews with 352 case patients and 646 controls and all of their parents.

Among the cases, 46% had astrocytoma, 6% had ependymoma, 8.5% had another type of glioma, 17.6% had primitive neuroectodermal tumors, 15.1% had other intracranial neoplasms, and 6.8% had unspecified intracranial neoplasms.

Similar proportions of cases and controls reported regularly using a cellphone (55% and 51%, respectively).

The researchers found that regular cellphone users were no more likely to have been diagnosed with brain tumors than nonusers.

Nor were kids who used cellphones for at least five years at increased risk compared with those who never regularly used them.

There were "somewhat elevated odds ratios without a clear exposure-response relationship" for other variables including time since first use, cumulative duration of subscriptions to services, cumulative duration of calls, and cumulative number of calls, the researchers said, but none of those reached significance.

Roosli and colleagues found no increased risk among regular users when looking at parts of the brain with the greatest exposure to radiofrequency energy -- the temporal and frontal lobes and cerebellum. But there was a significantly higher risk of tumors in parts of brain with lowest exposure (OR 1.92, 95% CI 1.07 to 3.44).

Nor was there any greater risk among those who used their phones predominantly on one side of the head, compared with those who held the phone as often on one side as the other.

In a subset of patients for whom recorded data on use were available from the phone companies -- 35% of case patients and 34% of controls -- there was a greater risk of brain cancer with a longer length of subscription to cellphone services (OR 2.15, 95% CI 1.07 to 4.29, P<0.001).

Yet risk wasn't related to cumulative hours of use in this cohort, they found.

The researchers noted, however, that these data are limited because they apply only to about a third of each cohort.

Other limitations include the fact that it is impossible to determine whether the children or others -- their friends, their parents -- made the calls.

The study was also limited by the small number of cases, which restricted its statistical power to detect small risk increases.

Use of cell phones may also have increased since the study was carried out; on the other hand, the type of phones used today may emit lower radiation, they said.

Despite the fact that the findings generally point to a lack of a relationship between cellphones and brain cancer in young patients, the researchers said they can't "rule out the possibility that mobile phones confer a small increase in risk" and called for future prospective studies -- adding that more retrospective studies won't help clarify the issue.

One such prospective study is the COSMOS trial, which will follow European cellphone users for at least 20 years.

In an accompanying editorial, John Boice, ScD, and Robert Tarone, of the International Epidemiology Institute in Rockville, Md., agreed that it's "impossible to prove a non-effect, and it will be debated whether and at what level additional research funds should be spent in assessing health effects associated with non-ionizing radiation especially in times of limited resources."

But Boice and Tarone called previous epidemiological study results "largely consistent and reassuring" that there's "no conclusive or consistent evidence that non-ionizing radiation emitted by cell phones is associated with cancer risk."

Still, they said they agree that incidence rates of brain cancer in the general population should continue to be monitored.

The study was supported by the Swiss Federal Office of Public Health and the Swiss National Science Foundation, as well as the Swiss Research Foundation on Mobile Communication, which counts several European communications companies among its founders and supporters.

The Danish CEFALO study was supported by the Danish Strategic Research Council; the Swedish cohort by the Swedish Council for Working Life and Social Research, the Swedish Research Council, the Swedish Cancer Society, the Swedish Childhood Cancer Society, and the Swedish Radiation Protection Authority. The Norwegian CEFALO cohort was supported by the Research Council of Norway.

Roosli reported previous relationships with Forschungsstiftung Mobilfunk, a nonprofit at ETH Zurich, which receives part of its funding from three Swiss mobile phone network operators.

A co-author reported relationships with the Danish utility industry and two mobile phone companies.

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